Massachusetts Citizens for Life praised Sullivan’s stances against the expansion of abortion rights in its endorsement of his candidacy for US Senate. He is seeking the Republican nomination in the April 30 special election primary.

“Michael Sullivan has been a fighter for the unborn and for the right to life of all,” said John Rowe, the group’s chairman, in a statement. “Sullivan will vote to prohibit abortion coverage under federal ‘multistate’ health plans, vote for parental notification and not bringing ­minor girls across state lines to have abortions without their parents’ knowing, and vote for conscience rights.”

Sullivan, a former US attorney, is the ­only one of the three Republican candidates who opposes ­legalized abortion. Daniel ­B. Winslow, a state representative from Norfolk, has said he supports abortion rights, while ­Gabriel E. Gomez, a Cohasset businessman, said he is personally opposed to abortion, but if elected he would not attempt to overturn current laws.

On the Democratic side, US Representative Edward J. ­Markey has been a longtime supporter of legalized abortion, while US Representative Stephen F. Lynch describes himself as an opponent of abortion, but has recent­ly said he would try to uphold Roe v. Wade in the Senate.